diff --git a/headers/os/interface/Size.h b/headers/os/interface/Size.h
index 2c687859b0..8c19f48346 100644
--- a/headers/os/interface/Size.h
+++ b/headers/os/interface/Size.h
@@ -11,7 +11,7 @@
 
 
 enum {
-	B_SIZE_UNSET		= -1,
+	B_SIZE_UNSET		= -2,
 	B_SIZE_UNLIMITED	= 1024 * 1024 * 1024,
 };